programming-for-dummies

16
The History of Computer Programming
So given these advantages of C or high-level languages, why would anyone
ever use machine language or assembly language? The answer is simple:
speed and efficiency.
If you want to write the smallest, fastest program possible, use machine
language because machine language is the native language of all computers.
Unfortunately, machine language is so hard to understand, write, and modify
that writing anything but small programs in machine language is nearly
impossible.
Rather than use machine language, most programmers use assembly language
when they need speed and efficiency. Assembly language creates small and
fast programs, but they’ll never be as small or fast as machine language programs.
That’s because processors understand only machine language, so
when you write an assembly language program, you have to translate that
assembly language program into machine language.
Translating assembly language into machine language by hand would be
slow and error-prone, so computer scientists have created special programs
that can do this automatically. These programs are assemblers.
An assembler takes an assembly language program and converts it into machine
language, but this conversion process isn’t perfect. That’s why assembly language
tends to create bigger and slower programs than equivalent hand-crafted
machine language programs. However, assembly language programs are much
easier to write and modify later than machine language, so assembly language is
used much more often than machine language.
High-level languages are much easier to write and understand than machine
or assembly language. The problem is that processors don’t understand
high-level languages either, so you have to translate a high-level language
program into equivalent machine language commands.
Doing this by hand is nearly impossible, so computer scientists have created
special programs — compilers — to do this for them. A compiler does nothing
more than take a program written in a high-level language and translates
it into equivalent commands written in machine language.
This translation process isn’t perfect so that’s why programs written in highlevel
languages tend to be much bigger and slower than equivalent programs
written in machine or assembly language. So when programmers want to create
large, complicated programs that still run fast and take up as little space as
possible, they tend to rely on the C programming language. That’s why so many
programs are written in C because C creates programs nearly as small and fast
as assembly language programs, while also being nearly as easy to write and
understand as high-level languages. (Note the emphasis on the word “nearly.”)